<!DOCTYPE html>
<html lang="zh">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		*{
			padding: 0;
			margin: 0;
		}
		.father{
			width: 330px;
			height: 330px;
			border: 1px solid black;
			box-sizing: border-box;
			display: flex;
			flex-wrap: wrap;
			flex-direction: row;
			justify-content: space-around;
			align-content: space-around;
		}
		.son{
			width: 100px;
			height: 100px;
			border: 1px solid red;
		}
	</style>
</head>
<body>
	<div class="father">
		<div class="son">1</div>
		<div class="son">2</div>
		<div class="son">3</div>
		<div class="son">4</div>
		<div class="son">5</div>
		<div class="son">6</div>
		<div class="son">7</div>
		<div class="son">8</div>
		<div class="son">9</div>
	</div>
</body>
</html>